Add enum to string function

PiperOrigin-RevId: 914243776

Author: Krzysztof Rymski

gemma/configs.cc

@@ -736,4 +736,23 @@ AttentionImpl GetAttentionImpl(const std::string& impl_name) {
   return AttentionImpl::kFlash;
 }
 
+std::string KVEncodingToString(KVEncoding encoding) {
+  switch (encoding) {
+    case KVEncoding::kF32:
+      return "F32";
+    case KVEncoding::kBF16:
+      return "BF16";
+    case KVEncoding::kF32TwoTranspositions:
+      return "F32TwoTranspositions";
+    case KVEncoding::kBF16TwoTranspositions:
+      return "BF16TwoTranspositions";
+    case KVEncoding::kInt8:
+      return "Int8";
+    case KVEncoding::kInt8TwoTranspositions:
+      return "Int8TwoTranspositions";
+    default:
+      return "Unknown";
+  }
+}
+
 }  // namespace gcpp

gemma/configs.h

@@ -92,6 +92,13 @@ enum class KVEncoding {
   kInt8TwoTranspositions = 6,
 };
 
+// Returns a string representation of the KVEncoding.
+// This representation will not change and can be used for
+// serialization or logging.
+// Note that no reverse function exists to convert a string back to a
+// KVEncoding.
+std::string KVEncodingToString(KVEncoding encoding);
+
 enum class AttentionImpl {
   kFlash = 0,  // Flash Attention (default)
   kFlashTransposedQs,